Question
Which one of the following is an endothermic reaction?
NDA
General Ability
General Science
2025
NDA 2025 (Phase 2)
NDA General Ability Question (2025) — Solution
Options
- A. CH_4(g) + 2O_2(g) CO_2(g) + 2O_2(g)
- B. C_6H_ 12 O_6(aq) + 6O_2(g) 6CO_2(g) + 6H_2O(l)
- C. N_2(g) + 3H_2(g) 2NH_3(g)
- D. 2Pb(NO_3)_2(s) 2PbO(s) + 4NO_2(g) + O_2(g)
Answer
D. 2Pb(NO_3)_2(s) 2PbO(s) + 4NO_2(g) + O_2(g)
Step-by-step solution
Combustion of methane (CH_4) is an exothermic reaction as it releases heat. The oxidation of glucose (C_6H_ 12 O_6) during respiration is an exothermic process that provides energy to living cells. The synthesis of ammonia (NH_3) from nitrogen and hydrogen (Haber process) is an exothermic reaction. The thermal decomposition of lead nitrate (Pb(NO_3)_2) requires heat to break down the reactant into simpler products (PbO, NO_2, and O_2). Since heat is absorbed, it is an endothermic reaction. Answer: 2Pb(NO_3)_2(s) 2PbO(s) + 4NO_2(g) + O_2(g)
Related: General Ability — General Science · All PYQ Banks